Theftproof lamp bulb



Nam 15, 192 7..

L. SCHMIDT, JR

THEFTPROOF LAMP BULB Filed 0013,. 50. 1926 INVENTOR Patented Naz s, 1921.

UNITED STATES PATENT OFFICE.

LAMBERT SCHMIDT, J'R., BROOKLYN, NEW YORK.

THEFTPROOF LAMP BULB.

Continuation of application Serial 110. 77,434, filed December 24, 1925. This application filed October 80,

1926. Serial No. 145,745.

This invention relates to theft-prooflamp bulbs and has for its primary object to prov standard lamp bulb is screwed into the standard socket, it is securely locked therein against the possibility of removal without first destroying the lamp bulb. It is a further object of this invent on provide a device for this purpose which entirely automatic in its action and requlres no manual operation other than the threading of the lamp into the socket in order to effect thelocking connection.

It is also an additional object of this invention to ovide means the form of a locking device within the usual empty chamber formed by the threaded plug of the standard base and to provide such means so correlated with the standard socket that no change in the bulb or in the standard socket s required. v

Heretofore it has been proposed to provio a theft-proof lamp by rearranging the construction of the base and socket requiring thereb a specially constructed base and a specia ly constructed socket. In other cases it has been proposed to provide a specially formed lamp bulb in which a certain portion other cases it has been proposedto supply certain means which require accurate registration and this is subject to the ob ect1on that in electrical contact work it is essen-' tial to make a close contact of the electric current bearin parts and this can only. be

done by provi ing a certain leeway in relabring about variations in t 0 end productions so that as is often the case, the threads of a base made by one manufacturer are used to engage the threads of a socket made of the locking mechanism is arranged. In

manufactured articles is sub'ected naturally by another manufacturer,-in consequence all of wh1ch a certain variation results, and due to such variation together with a deslre to obtain a frictional full surface contact as already pointed out, a locking device operating in accordance with a pre-determined registration is precluded. It has also been proposed to provide a locking device which operates upon the flat surface of one end of the base, but this has many objections since it is not fool-proof in that a sharpened point does not necessarily always lock and engage a plane surface, and if such a locking engagement is not brought about, it is clear that a theft-proof lamp is not provided.

Other means have been proposed but the commercial market either on account of the expense inherent in such means, or their inefliciency of operation in failing to give a fool-proof device, has not as yet generally adopted such means. The expense of such means is a very-important consideration in that lamp bulbs with their standard bases are sold competitively under. prices which preclude any considerable addition thereto, and one object of this invention is to provide a device which at an almost insignificant cost can be readily made part of a "standard lamp base, without change of an kind in the standard socket of in the stan' ard bulb. The cost of a device in accordance with this invention is less than one-half a cent b A further object of this invention forming' an added feature to the structure prov1 ing a theft-proof lamp consists 1n the pzovision of an auxiliary device which may set in operation to enable a theftroof lamp to be made non-theft proof. Wit the use of this auxiliary device a very important desideratum has been complied with in that one criticism of atheft-proof lamp is that it can only be used in such cases where a theft-proof lamp is desired. There are cases however in the use of lam user likes to have the privilege of removing his lamp bulb unimpeded b the locking device and in order to supp y the wants of such users the provision of the referred to auxiliar device has been made. By these means t e purchaser of lamps in quantity can acquire vhis supply of lamps normally .non-theft-proof and when he desires that certain of these lamps be made theft-proof he bulbs where the merely sets the locking device into operative position before screwing the base into the socket.

In view of the foregoing, the invention fundamentally consists in the provision of a locking device interposed between the threads of the base and the threads of the socket. This locking device is so arranged and of such configuration that on the un screwing of the base a secure lock is obvice protruding from the base having a dif ferent pitch movement than the pitch of the thread of the socket, isjammed into the valley of the thread of the socket whereby in addition to its piercin action a jamming action is provided and t ereby a secure hold is obtained, As an added feature over the foregoing, ameinber is provided to hold the locking device within the base to such an extent that when the base is unscrewed from the socket the locking device will not engage in locking fashion the threads of the socket. This member is operative from the exterior of the base and when so oper-' ated releases the locking device into a position whereb it may readily engage the threads of t e socket as hereinbefore described.

The invention consists of certain further I features which will be more fully described hereinafter which are shown in the accompanying drawings, together with the features hereinbefore referred to, and will be finally pointed out in the claims.

In the accompanying drawings showing various embodiments of my invention and in which similar characters of reference indicate corresponding parts throughout the venous views,

Figure 1 is a side elevation of my imroved theft-proof lamp, the socket shell ein shown 1n section and the lamp. bulb artially broken away as such a bulb can ave any configuration as also any arrangement of filament as is well known.

Figure 2 is an end elevation looking into a standard base with the bulb and electrical connections removed therefrom, said base having my invention applied thereto.

Figure 3 is .an enlarged vertical section taken on line 3-3 of Figure 1.

Fi re 4 is a horizontal section taken on the line 4-4 of Figure 3.

Figure 5 is a section of a convolution of the base and of the socket with a space between these convolutions somewhat exagger pitch line of the vFigure 7 shows another view of the parts shown in Figure 5' in which the base unscrews from the socket and in which the locking device has a different pitch line from the pitch line of the base and the pitch line of the socket jams itself into the thread of the socket.

Figure 8 is a diagrammatic view of lines of the threads of the socket and the pitch line of the point of the locking device showing the manner in which on the rotation of the base a. jamming action takes place.

Figure 9 is a diagrammatic view of the pitch line of the base and the pitch line of the point of the locking device.

Figure 10 is a plan view of the interior of a standard base showing my improved locking device and also showing the means provided for placing such locking device into inoperative position, the locking device being shown in locking position and the member controlling its movement being shown inoperative.

Figure 11 is a similar plan view of the same parts with a locking device in inoperative position and the member controlling it in operative position taken on line 11-11 of Figure 12.

Figure 12 is a section taken on line 12--12 of Figure 11, and Figure 13 is a partial front view of the locking device and the safety auxiliary device for holding the locking device in inoperative position.

In the drawings the glass bulk 15 encloses filament 16 and the bulb is provided with the base 17 of standard construction having its contact point 18 at its free end. The

base 17 is threaded to provide exterior threads and is usuall formed'of a metallic shell, with a hpllow interior through which the electrical connections pass. The socket of standard construction is indicated by 19 having the usual opening 20 to permit the contact point 18 of the base to pass therethrough and having its usual opening end 21 to permit the free entrance of the threaded base. The standard base 17 is provided with aslot 22 preferably of elongated shape and running alon concentrically with the base threads or arranged at a slight angle thereto. Within the base 17 there is arranged a springlike member'23 preferably a piano wire which is secured at one of its ends 24 to the interior wall of the by a locking base by solder dr the like, and then extends around the interior of the base following a convolution of a thread and seated within the valley of the thread until it terminates in a pointed end 25 having a sharp point normally protruding through the opening 22 of the base and a short distance exterior to the peripheral surface of the base. The arrangement of the wire 23 is shown in Figure 4 and the protruding sharp point 25 is clearly shown in Figure 2. In order to provide means to remove the pointed end 25 of the wire 23 out of engagement with the wall of the socket 19, the wire 23 is provided with a bent portion 26 of a suitable configuration to permit the entrance therein of a simple tool. When the lamp bulb has been broken and entrance has been provided into the intcrior of the base the tool enters into the bent portion 26 and by suitable pressure the point 25 is removed from the socket 19 and thereby the base may be removed from the socket.

In view of the shape of the pointed end 25 and the resilient character of the wire 23 and its freedom of movement within the base, the base may be readi'liy screwedinto the socket without the pointed end of the wire permanently engaging the socket interior. When, however, the base is unscrewed, then an engagment of the pointed end 25 with the interior of the socket' 19 takes place to such an extent that the base cannot be unscrewed any further and thereof the base to the socket is provided. further unscrewing of the base can only take place when the lamp bulb has been destroyed and access to the interior of the base thereby provided. The locking action of the pointed end of the wire 23 results from various actions. The end is sharply pointed in order to brin about a rapid entrance of the sharpene point of relatively hard material into, the relatively soft material of the socket shell. In addition to this there is a certain amount of clearance between all threads and particularly so between threads made without consideration of accuracy as is the case with lamp bases and socket threads, and by virtue of this clearance when the base is rotated for the purpose of unscrewing. the clearance that is provided requires a certain movement of the base in respect to the socket which might be compared to a lost motion take-up. As a result of this a divergence of the angular relationship of the pitch lines of the threads of the base and the threads of the socket take place. Thisis shown in somewhat exaggerated manner in Figures 5 and 6, and such disposition of the clearance between the threads is caused also by the action of the sharpened point of the wire whereby the clearancebetween the threads becomes. larger, at the portion ofthe circumference where the wire engages the socket than in its diametrical opposite direction. In consequence of this, as'will be seen in Figure 6, a gradually converging space between the exterior of the base and the interior of the socket is provided. In view of this, an eccentricity rather than aconcentricity results and the sharpened pointed end 25 is thereby brought into a most favorable position to iammingly lock with the socket wall. Not alone is this true when considered from a plan view aspect as shown in Figure 6, but also in relation to a vertical view aspect as shown in Figure 5. In the embodiment shown, the pitch line of that portion of the wire 23 which protrudes from the interior of the base has a different angular relationship to a plane at right anglesto the axis, than the pitch line has which determines the thread of the base. This divergence of angular relationship of pitch line of locking member and pitch line of' base thread is clearly seen in Figures 7 and 9, and by the unscrewing action of the base the sharpened pointed end is jammed against the side of the pitch line as shown clearly'in Figure 9 and thereby another preferential relation ship of parts is provided to cause an engagement of the pointed end of the wire with the wall of the .socket. Other mechanical actions will be clear to one skilled in the art. But it will be seen that the summation and jointure of the actions results in a very secure locking of the locking member with the socket and hence, a very secure locking of the lamp in non-theft position.

As has been pointed out, lamps constructed in accordance with the foregoing .when the base is once inserted .into the socket, become theft-proof and cannot be used in such cases where a replaceable or a non-theft-proof lamp is desired.

In order to comply with certain conditions of usage, I provide the locking wire-or other locking member, for instance, the flat springlike resilient member 30 shown in Figure 10, with a. stirrup 31.' This stirrup clearly shown in Figure 12 has a part engaging an opening 32 in the member 30 and is so arranged as to be pivotally swingable.

This stirrup 31 is shown in non-operative position in Figure 10 permitting thereby the projection of the sharpened end point 33 protruding from the base. When it is desired to make the locking device inoperative, the stirrup 31 is moved or swung into position shown in Figure 11 substantially radial to the circumference of the base whereby it 1 holds the member 30 in such a position within the base that the point 33 does not protrude therefrom. The lamps embodying this stirrup device to make the lockin member inoperative are supplied to the user with a stirrup in. the position shown in Figurell. It will be noted that the end of the stirrup bridges the slot 22 of the base and is visible through the slot or opening 22 when looking towards the interior of the base as in Figure 13. As stated the lamps are provided to the user with the part in position as shown in Figure 11. The user then takes a small sharp tool or the like, or utilizes his thumb nail and moves the stirrup 31 along the slot whereby due to the change in its angular position from its locking radial position, and due to the action of the resiliency in the member 30, the stirrup 31 will spring away from its locking position into the position shown in Figure 11, and simultaneously the sharpened point 33 will protrude from the wall of the base, This stirrup acts against an abutment 40, as in Figure 10. When in such a position the lamp is ready to be inserted into the socket as hereinbefore described. By the arrangement of these parts,

' a non-theft proof lamp is provided which,

however, has the capacity of being made theft-proof.

Referring again to Figures 10 to 13, the resilient member 30 instead of being a piano wire as that shown in Figure 4, has a flat piece of metal seated within a valley of a thread and having one end secured at 34. Its other end is free to move in the same manner as described'in connection with Figure 4. A fiat metallic member 30 has an elongated opening 35 for the insertion of a tool to move itfrom locking position into unlocking position when the lamp bulb hasbeen broken.

It will thereforebeseen from the forego.-.-

ing, that an improved theft-proof lamp has been provided with means that are most simple and inexpressive. The arrangement of the means is such that a ver secure hold is obtained. The means for coking are arranged between the threads of the base and socket and have such an operation that the locking action can take place at any desired point'of travel of the base threads. In respect to the lamp threads, the end point of travel usually being where a most efficient contact is established, which difi'ers with each and every lamp. By the recognition of the presence of clearances between the threads and the forcing of the locking member into the gradual conver ing opposed divergence of the angular relationship of the threads of the base and the threads of the socket, and the divergence of the pitch line of the above in respect to the pitch lineof the protruding locking member, various co-acting mechani-' cal dispositions are provided to combine to obtain a natural secure hold or lookin action. By suchco-actions an intended theftproof lamp becomes one in actuality. By the provision of means to hold the locking mem ber in dormant position and readily brought into activity without the use of a tool, or a tool of the simplest kind, a non-theft-proof lamp usable for all purposes where an ordi- Among the advantages of my invention may be pointed out the simplicity of construction, the utilization of a standard base and a standard socket, the avoidance of any special lamp bulb or any special base or socket, the provision of locking means between the threads where due to the actions described an efiicient locking is made possible, and the almost insignificant cost of'the small piano wire as an example, with the provision of the slot in the base.

I have described various embodiments,

but it is clear that changes might be made therein without departing from the spirit of my invention which is defined in the annexed claims.

' This is a continuation in part of my application Serial Number 44,415, filed'July 18, 1925, and is a continuation of application Serial No. 77 ,434, filed December 24, 1925.

I claim:

1. In combination, with a standard-lamp bulb having a standard lamp base member with exterior threads, and a standard lamp socket member having exterior threads, of means interposed between said threaded members and inaccessible 'when the lamp bulb is intact and the threaded members engage each other, and accessible only when the lamp bulb is broken, said means comprising a resilient spur on one of said threaded members engaging the-threads of the other member and permitting relative movement of said members in one direction only throughout the length of the threads of said member, and means for holding theresilient.

spur within the wall of the base member, said means being operative from the exterior of the base member into a position allowing the spur to protrude from the base.

2; In combination, with a standard lamp base member with exterior threads, and a standard lamp socket member having exterior threads, means interposed between the base member and the socket member for locking the same in positiomand means for holding the locking member in inoperative position or in operative position, said means for holdingthe locking member in inoperative positioncomprising a stirrup adapted to be placed in radial position for locking the locking member within the base member and said stirrup being adapted to be moved with in the base member from its locking position to a position permitting the locking member to protrude from the base member.

3. A theft proof lamp composing a standard lamp bulb with standard lamp, base as I having a-plug shell with exterior threads and having an opening in line with the line of the threads in its threaded wall,

I ship with the line of the threads and slid ingmounted within said plug shell and provided with a spur urged through said opening, said spur pressing against the wall of the opening nearest the free end of the plug shell; and a standard socket having interior threads engaged by the threads of the base, saidspur having an angular relationin the socket threads onthe screwing in-- o'f the base and entering into the angular blte formed by the threads to form a locking en-. gagementto lock the lamp base within said socket against rotation in opposite direction and preventing removal of the lamp base.

4. In combination with a standard lamp base member with exterior threads and a standard lamp socket member having interior threads, means interposed between the threads of the base member and the socket member for locking the same in position, and means operable only when the lamp is out of its normal operative engagement with the lamp socket, for holding the locking member in inoperative position or in operative position. I

5. An electric incandescent lamp, comprising a standard glass bulb having a frangible base mounted in a standard exteriorly threaded metallic base, said metallic base being provided with a slot in the threaded ortion thereof, and an elongated resilient ocking element mounted inside said metallic base and lying in a valley of the threaded base, having one end projecting out through said slot and adapted to bite into the interior of a mounting socket, the major portion of the locking element being within the metallic base and accessible only by break-. ing through the glass bulb and frangible base.

6. An electric incandescent lamp, comprising a standard glass bulb having a frangible base mounted in a standard exteriorly threaded metallic base, said metallic base being provided with a slot in the threaded portion thereof, and an elongated resilient lockingelement mounted inside said metallic base and lying in a valley of the threaded base, having one end projecting out through said slot and adapted to bite into the interior of a mounting socket, said locking element having a projection adapted to be engaged by a releasing tool, the projection and the major portion of the locking element being withinthe metallic base and accessible to the releasingftool only by breakliong through the glass bulb and frangible ase,

' 7. An electric incandescent lamp, comprising astandard glass bulb having a frangi- 'ble base mounted in a standard exteriorly threaded metallic base, said metallic base being provided with a slot through the threaded portion, and a resilient locking element mounted inside said threaded base and having one end extended outwardly through said slot and adapted to bite into the interior surface of the usual socket, said looking element being provided with a projection adapted to be engaged by a releasing tool, said projection and the major portion of the locking element being within the metallic base and accessible tothe releasing tool only by breaking through the glass bulb and fran ible base. I v

8. An eectric device comprising a frangible membermounted in a standard exteriorly threaded metallic base, said metallic base being provided with a slot in the threaded portion thereof, and an elongated resilient locking element-mounted inside the metallic base and lying in a valley of the threaded base, having one end projecting out through said slot and adapted to bite into the inte'rior' of a mounting socket, the major portion of said locking element being within the metallic base and accessible only by breaking through the said frangible member.

In testimony that I claim the foregoing as my invention I, have signed my name hereto. v

LAMBERT SCHMIDT, J B. 

